// Single-class person detector — Icarus Verilog compatible
// All weights from analytical least-squares. Zero training. 4,614 bytes INT8.

module person_detector #(
    parameter FEAT_DIM = 768,
    parameter BIT_WIDTH = 8,
    parameter ACC_WIDTH = 24
)(
    input  wire signed [BIT_WIDTH-1:0] features [0:FEAT_DIM-1],
    output wire signed [ACC_WIDTH-1:0] person_score,
    output wire signed [ACC_WIDTH-1:0] box_ltrb [0:3],
    output wire signed [ACC_WIDTH-1:0] centerness,
    output wire detection
);

    reg signed [BIT_WIDTH-1:0] cls_w [0:FEAT_DIM-1];
    reg signed [BIT_WIDTH-1:0] reg_w [0:4*FEAT_DIM-1];
    reg signed [BIT_WIDTH-1:0] ctr_w [0:FEAT_DIM-1];

    initial begin
        $readmemh("rom/person_cls_w.hex", cls_w);
        $readmemh("rom/person_reg_w.hex", reg_w);
        $readmemh("rom/person_ctr_w.hex", ctr_w);
    end

    // Classification: sum(features[d] * cls_w[d])
    reg signed [ACC_WIDTH-1:0] cls_acc;
    integer ci;
    always @(*) begin
        cls_acc = 0;
        for (ci = 0; ci < FEAT_DIM; ci = ci + 1)
            cls_acc = cls_acc + features[ci] * cls_w[ci];
    end
    assign person_score = cls_acc;
    assign detection = (cls_acc > 0);

    // Box regression: 4 dot products
    reg signed [ACC_WIDTH-1:0] reg_acc [0:3];
    integer ri, rj;
    always @(*) begin
        for (ri = 0; ri < 4; ri = ri + 1) begin
            reg_acc[ri] = 0;
            for (rj = 0; rj < FEAT_DIM; rj = rj + 1)
                reg_acc[ri] = reg_acc[ri] + features[rj] * reg_w[ri * FEAT_DIM + rj];
        end
    end
    assign box_ltrb[0] = reg_acc[0];
    assign box_ltrb[1] = reg_acc[1];
    assign box_ltrb[2] = reg_acc[2];
    assign box_ltrb[3] = reg_acc[3];

    // Centerness: sum(features[d] * ctr_w[d])
    reg signed [ACC_WIDTH-1:0] ctr_acc;
    integer cti;
    always @(*) begin
        ctr_acc = 0;
        for (cti = 0; cti < FEAT_DIM; cti = cti + 1)
            ctr_acc = ctr_acc + features[cti] * ctr_w[cti];
    end
    assign centerness = ctr_acc;

endmodule